Scythe is probably underestimating his previous creations when he says he thinks the new dolls are better, particularly Reiji, who he only brainwashed. It was Elen and Claudia who "raised" Reiji to become the killer that he is, capable of killing one of those most important to him, not because he is cold-blooded, but because he has gained a resolve and ambition that allowed him to sacrifice as much.

Scythe is probably underestimating Elen as well, thinking that she is still the soulless doll she was before. Being with Reiji has changed Elen, particularly in her ability to rebel against Scythe.